Ultrasonographical identification of the superficial circumflex iliac artery as a landmark for location of the femoral nerve in dogs

Objective

To investigate the utility of identifying the superficial circumflex iliac artery (SCIA) via ultrasound as an anatomical landmark for ultrasound-guided femoral nerve block.

Study design

Observational study.

Animals

A group of six canine cadavers weighing >20 kg.

Methods

Pelvic limbs from six canine cadavers were examined to study the relationship between the SCIA and the femoral nerve. Ultrasonographic imaging of the SCIA in each limb was obtained with the transducer placed transversely in the medial aspect of the pelvic limb at the inguinal area. Subsequently, a needle was inserted in close proximity to the femoral nerve using an in-plane technique based on the anatomical relationship between the SCIA and femoral nerve. A total of 0.1 mL of colored latex was then injected at the location where the femoral nerve was expected to be in relationship to the SCIA. Gross dissection of the inguinal region in each pelvic limb was performed after injection. Positive nerve location was defined when the colored latex was in contact with the femoral nerve.

Results

A total of eleven pelvic limbs were injected because the SCIA could not be successfully visualized in one limb. Upon dissection, colored latex was found to be in direct contact with the femoral nerve in all 11 injected limbs.

Conclusions and clinical relevance

We concluded that the ultrasonographic visualization of the SCIA assisted in the accurate deposition of dye in proximity to the femoral nerve of canine cadavers. Further investigation will determine the efficacy of this technique for performing femoral nerve blocks.